JP2020059646A5 - - Google Patents

Claims (11)

A tubular preform having an outer diameter D _OD , an inner diameter D _ID , and a diameter ratio D _rel (however, D _rel = D _OD / D _ID ) is softened for each band in a heating region heated to a drawing temperature T _draw . From the softened region, a capillary list land (1; 41) having an outer diameter d _OD , an inner diameter d _ID , and a diameter ratio d _rel (where d _rel = d _OD / d _ID ) at a drawing speed v _draw . In a method of manufacturing a glass capillary tube (1; 41), comprising a method step of continuously drawing the capillary tube (1; 41) from the capillary list land, the capillary hole (2; 42) is formed. In the heating region, a shrinkage process based on the influence of the drawing temperature T _draw and the surface tension is applied so that the diameter ratio _{drell of the capillary listland (1; 41) is at least 5 more than the diameter ratio D rel of} the preform. Adjusted to a doubled value, where the preform used is a multimode optical fiber preform or a single mode optical fiber preform having a preform core surrounding the internal holes and a preform cladding surrounding the preform core. Then, from the preform, a capillary list land (1) having a capillary core (3; 43) surrounding the capillary hole (2; 42) and a capillary clad (4; 44) surrounding the capillary core (3; 43). 41) The above-mentioned method, which comprises drawing a line. The delineation temperature T _draw that results in the shrinkage process is determined in an iterative process, and the iterative process is the following method step:
(A) A step of heating the heating region to a temperature T ₁ , where T ₁ <T _draw holds.
(B) A step of drawing a capillary partial strand by the heating region heated to the temperature T ₁ .
(C) A step of determining the diameter of the capillary hole of the capillary partial strand and ensuring that the diameter is larger than the desired inner diameter of the capillary hole.
(D) A step of raising the temperature of the heating region from T ₁ to the drawing temperature T ₂ and drawing a further capillary partial strand by the heating region heated to the drawing temperature T ₂ .
(E) A step of determining the diameter of the capillary hole of the additional capillary partial strand and confirming whether the diameter is within an acceptable fluctuation range before and after the desired inner diameter.
(F) When the diameter of the capillary hole is within the fluctuation range before and after the desired inner diameter, T ₂ = T _drive holds; the diameter of the capillary hole is larger than the desired inner diameter including the allowable fluctuation range. If is also large, then T ₂ <T _draw holds and the iteration process is continued in method step (d) with a default value of T ₁ = T ₂ ; the diameter of the capillary hole is greater than the desired inner diameter including the variation range. The method according to claim 1, wherein if it is also small, T ₂ > T _draw holds, and the iterative process is continued in the method step (a), comprising the step. The method steps (c) and (e) are characterized in that the diameter of the capillary hole (2; 42) is determined between the drawing of the capillary list land (1; 41) or the drawing of the additional capillary list land. The method according to claim 2. The method according to any one of claims 1 to 3, wherein the drawing speed v _draw is adjusted in the range of 5 to 100 m / min. The method according to any one of claims 1 to 4, wherein the capillary list land (1; 41) is withdrawn at a stretching ratio in the range of 900 to 200,000. For the preform and the capillary list land (1; 41)
D _OD > 15 mm
D _ID > 1 mm
D _rel <30
d _OD > 100 μm
d _ID <1 μm
d _rel > 100
The method according to any one of claims 1 to 5, wherein the above is satisfied. About the capillary list land (1; 41)
100 μm <d _OD <500 μm,
0.1 μm <d _ID <1 μm, and 100 <d _rel <5000
The method according to any one of claims 1 to 6, wherein the above is satisfied. About the preform
15mm <D _OD <45mm,
1,000 μm <D _ID <5,000 μm, and 3 <D _rel <30
The method according to any one of claims 1 to 7, wherein the above is satisfied. For the preform and the capillary list land (1; 41)
2,000 <D _ID / d _ID <50,000
d _rel / D _rel > 10 and d _rel / D _rel <300
The method according to any one of claims 1 to 8, wherein the above is satisfied. The method according to any one of claims 1 to 9, wherein the heating region is formed in a tubular furnace having a circular heating internal space. The capillary core (3; 43) has a cross-sectional area CSA _KK , the capillary clad (4; 44) has a cross-sectional area CSA _KM , where the preform core has a cross-sectional area CSA _VK . A preform in which the preform clad has a cross-sectional area CSA _VM is used, wherein CSA _KM / CSA _KK = CSA _VM / CSA _VK holds for each of the cross-sectional area ratios of the clad and the core. The method according to claim 1.